You're correct, these things are entirely subjective. My appreciation for Queensryche has nothing to do with commercial comparisons between it and other bands. I actually enjoy listening to non-mainstream bands because of the uniqueness of the sound--for me, Tate was part of that sound. Which is I why I loved Operation Mindcrime (a "concept" album) and stopped listening when they came out with Empire, which was purely designed for radio play and mass appeal.

I will say that Tate, while controversial, is widely regarded as a pioneer in the progressive metal community, and many in that community admit to being influenced by him. No greater authority than Wikipedia has this to say: "Tate is ranked fourteenth on Hit Parader's list of the 100 Greatest Metal Vocalists of All Time. He was voted #2 on That Metal Show's top 5 hard rock vocalists of the 80's. In 2012, Sally Steele presented him with the Vegas Rocks Magazine Award for 'Voice in Progressive Heavy Metal.'" If that doesn't convince you, nothing will! Yes, that last part was entirely TIC. Rock on!